Zenia Barnard, Ph.D. Do you have a source for that Mathilde is the mother and not Beatrix that is also stated as mother? As I understand, both are wives of Dietrich I
When in doubt, always check Medieval Lands: https://fmg.ac/Projects/MedLands/CONTENTS.htm
The Counts of Cleves are under "Lower Rhine Nobility" https://fmg.ac/Projects/MedLands/FRANCONIA%20(LOWER%20RHINE).htm#_T....
Looks like your "Dietrich II" is MedLands' "Dietrich I", and there are no clear links above him.